Spring.



n. LANDAU, SPRING.

APPLICATION FILED SEPT- l3| ISIG.

. Patented Oct. 2,1917.

. lNl/ENTUR A TTORNEY which result in UNITED STATES navm LANDAU', or new roan, n. Y. srnmc.

Specification of Letters Patent.

Patented Oct. 2, 1917.

Application filed September 18, 1918. Serial No. 119,814.

To all whom it may concern:

Be itknown that I DAVID LANDAU, a citizen of the United tates, residing in the city, county, and State of, New York, have invented certain new and useful Improvements in Springs, of which the following is a s ecification.

my Patent No. 1,199,013, dated September 19th, 1916, have disclosed and claimed certain fundamental improvements in the construction (if laminated springs,

t y improvin sprin s of that character i y increasing the eflicienc y thereof for the wei ht of metal used; increasing the load waich such springs can carry, making the spring more durable; improving the interaction of the several leaves and the stress relationship existing between them; and producing a more satis factory stress distribution in the individual leaves. I have also discussed in said patent the importance of properly tapering the ends of ring leaves, the mode of action of tapered eaves and the theory and underl'ymg principles of scientific tapering which were not theretofore known.

A v important feature of my invention set 150:3 in said patent consists in the use of an im roved system of tapering the leaves by which a greater deflection efiiciency of the leaves is obtained. The present application, which is in part a division of the application for my patent referred to relates rimarily to a particular form of taper emodying the Broad invention set forth'in said prior atent. Other features of the present app ication relate to a construction for maintaining the leaves of laminated sprin s in alinement, to means for improvingt e lubrication of the leaves and to an im roved form of stress rectifying slot.

11 the accompanying drawings, which form a part of this s ecification and which illustrate :certain prei rred embodiments of the invention, Figure 1 is a side elevation of a semi elliptic spring. Fig. 2 is a bottom plan view of a-portion of the spring shown in Fig. 1. Fig. 3 is a fragmentary side elevation, partly in vertical section, of portions of the intermediate leaves of the spring shown in Fig. 1. Fig. 4 is a plan view of a portion of one of the leaves. Fig. 5 is a side elevation of a modified form of spring embodying my invention. Fig. 6 is a bottom plan view of a portion of the spring shown in Fig. 5.

Fig. 7 is a dia- Referring to the drawings in detail and particularly to Figs. 1, 2, 3, and 4, the numeral 1 designates a semi-elliptic spring having a master leaf 2, which is provided at its ends with the usual eyes 3, which receive the shackle bolts by which the spring is attached to the su ported load such as a vehicle body. 4 is t e long plate, 5 is the short plate and 6 are a series of intermediate plates, which may be more or less in number in accordance with the stren h of the spring desired and the weight 0 the load to be supported. As illustrated the leaves are inversely graded in thickness in accordance with the principles and for the reasons set forth in my previous patent, the master leaf being the thinnest and the short plate the thickest. These figures also illustrate certain other features of construction disclosed in my said patent, such as that the ends of the leaves below the master leaf are provided with tapered portions 7, which increase in fineness from the shorter toward the longer plates, the end of each taper overlapping the base of the taper of the next longer plate.

The form of the taper 7 to which the present invention is particularly directed is illustrated in Figs. 1 and 2 and in greater detail in Figs. 7, 8, and 9. It will be seen that in the first place, the leaves are tapered at their end portions both in thickness and in Width, the ta er in thickness being in the general form 0 a trapezoid as particularly set forth and broadly claimed in my previous patent. That is to say, referring to Fig. 8, the taper in its elemental form with the leaf developed so that it is straight has the outline in the plane of its thickness of a trapezoid a, b, o, d, the taper in this plane being defined by two plane surfaces, which if continued to a line of intersection would come together at a point e. Looking at the leaf in plan, it will be'seen that the taper in width is also a trapezoid, f, g, h, i, this taper being defined by vertical plane surfaces which as illustrated would also intersect at e. Theoretically the taper might be carried out to a sharp point at e but for practical reasons of manufacture and use, I deem it referable to omit the sharp point as it perorms no useful function, might break off, would tend to abrade the surface of the plate above and also introduces difficulties in the proper heat treatment of the leaves. In using the term trapezoid in definin these tapers, I use it as a convenient mode 0 expression in defining my characteristical novel form of taper rather than as a strict geometrical descriptive term and the taper might be described in other words as one having a decrease in width and thickness as it proceeds from its base in accordance with a linear function of the distance from the base of the taper.

Fig. 9 shows the ta ered leaf illustrated in Figs. 7 and 8 curve as is frequently done in practice, the essential characteristic of the taper as trapezoidal in the sense in which I have defined this term being preserved in that the same linear thickness and width relationship is retained and this taper, of-course, falls within the term trapezoid as I have employed it.

The form of taper above described. namely, one which is trapezoidal both in thickness and width has high flexual characteristics and a very high deflection efii'ciency. In fact as I have ascertained by calculation and experiment, the deflection efliciency of a tapered leaf end of this form is at least fifty per cent. greater than the deflection efliciency of a similar overhanging leaf end which 1s not tapered. This novel form of taper is also particularly advanta eous when used in connectionwlth other fiaatures of invention of my revious patent such as when it is so embed e in a spring that the ends of the tapers of the shorter leaves overla the bases of the tapers of the next longer eaves.

This taper is also ve advantageously utilized in connection wlth my inversely graded form of spring in which the leaves decrease in thickness from the short plate to the master leaf and also in which the tapers increase in fineness from the short plate to the master leaf (see Fig. 1). This form of taper, however, is not limited to use in such a spring, but is generally applicable to spring construction and may be employed with other forms of springs such as that described in my application,.Serial No. 116,284 filed August 22nd, 1916. I have illustrated the present invention in connection with. such a spring in Figs. 5 and 6, in which the leaves increase in thickness from the short plate to the master leaf, the tapers decreasing in fineness in the same direction. As explained in my said application, Serial No.

16.284, a spring of this character has advantages for certain classes of work as when called upon to act as a strut when carrying the rear axle of a motorrepelled vehicle.

My improved form 0 taper may also be advantageously employed in connection with leaves provided with stress rectifying slots as described in my previous patent and one form of which is illustrated in Figs. 3 and 4. a

Referring specifically to Fi s. 3 and 4, it will be seen that the interme iate leaves of the spring are provided near their ends with stress rectifying slots, which as illustrated are so shaped as to provide enlarged outer portions 10 from which extend narrower parallel sided ortions 11. This form of slot is desirab e for its stress rectifying roperties, the greatest metal deletion bemg toward the outer end where it is usually least necessary and the parallel sides of the inwardly extending portions may be advantageously used as guides to wcperate with a projection or head 12 formed on the adjacent shorter leaf, which acts to hold the leaves in proper alinement. At the same time any necessary relative movement may take place between the leaves when the spring is deflected as the bead will slide between the parallel walls.

As described in'my previous patent, the slots may also be advantageously employed as a means for lubricating the leaves and the bead coiiperates with this function of the slotin agitating and distributing lubricant contained therein and assisting in forcing the same between the leaves.

While I have shown and described in detail certain particular examples of springs, these are to be understood merely as illustrative of preferred embodiments of the principle of my invention and I do not desire to limit myself thereto but intend to cover every construction in which the principle of my invention is embodied.

Having thus described my invention, I claim:

1. A leaf for a laminated spring having tapers in the plane of, its thickness and in the plane of its width. both of said tapers having the outlines of a trapezoid.

2. A laminated leaf spring comprising a plurality of leaves having central portions of substantial length and of uniform dimensions in thickness and width. said leaves having end portions tapered in the planes of their width and thickness in the outlines of a trapezoid, the ends of the tapered portions of the shorter leaves overlapping the bases of the tapers of the respective next longer leaves.

3. A leaf for a laminated spring having its end portion tapered both in the plane of its width and plane of its thickness, the taper in both planes having the outlines of a trapezoid, said leaf being provided adjacent to the blase of the taper with a stress rectifying s 0t.

4. A laminated leaf spring in which certain of the leaves have end portions tapered in both the planes of thickness and width,

the taper in both planes having the outlines ,of a trapezoid, the ends of certain of the leaves being also fying slots within t provided with stress rectie areas covered by the 5 ends of the next shorter leaves.

5. A laminated leaf spring in which certain of the leaves are the end provided with stress rectifying slots within th e areas covered by next shorter leaves,

10 said shorter leaves being provided with beads cooperating with the w the adjacent longer lea leaves in alinement.

alls of said slots in ves to maintain the 6. A leaf for a laminated spring provided with a stress rectifying slot having an enlarged outer portion and a parallel sided inwardl extendin portion.

7. A aminated fiaaf spring having lubricant pockets in the end portions of certain of the leaves within the areas covered by ends of the next shorter leaves, said shorter leaves being provided wit projections axtending into said lubricant pockets for agitating the lubricant therein.

DAVID LAN DAU.

the, 20 

